An overview on how failure analysis contributes to flight safety in the Portuguese Air Force

Failure analysis has been, throughout the years, a fundamental tool used in the aerospace sector, supporting assessments performed by sustainment and design engineers mainly related to failure modes and material suitability. The predicted service life of aircrafts often exceeds 40 years, and the design assured life rarely accounts for all in service loads and in service environmental menaces that aging aircrafts must deal with throughout their service lives. From the most conservative safe-life conceptual design approaches to the most recent on-condition based design approaches, assessing the condition and predicting the failure modes of components and materials are essential for the development of adequate preventive and corrective maintenance actions as well as for the accomplishment and optimization of scheduled maintenance programs of aircrafts. Moreover, as the operational conditions of aircrafts may vary significantly from operator to operator (especially in military aircraft), it is necessary to access if the defined maintenance programs are adequate to guarantee the continuous reliability and safe usage of the aircrafts, preventing catastrophic failures which bear significant maintenance and repair costs, and that may lead to the loss of human lives. Thus being, failure analysis and material investigations performed as part of aircraft accidents and incidents investigations arise as powerful tools of the utmost importance for safety assurance and cost reduction within the aeronautical and aerospace sectors. The Portuguese Air Force (PRTAF) has operated different aircrafts throughout its long existence, and in some cases, has operated a particular type of aircraft for more than 30 years, gathering a great amount of expertise in: assessing failure modes of the aircrafts materials; conducting aircrafts accidents and incidents investigations (sometimes with the participation of the aircraft manufacturers and/or other operators); and in the development of design and repair solutions for in-service related problems. This paper addresses several studies to support the thesis that failure analysis plays a key role in flight safety improvement within the PRTAF. It presents a short summary of developed

Experiencia colombiana en reparación de núcleos de transformadores de potencia

Este artículo presenta el reporte de caso sobre fallas presentadas en el núcleo de transformadores de potencia y algunas experiencias técnicas y metodológicas en la reparación parcial y total de los mismos a varias unidades, hechas en Industrias Explorer Ingeniería S. A. S., empresa dedicada al mantenimiento y reparación de transformadores. También es presentada la metodología para la selección del tipo de lámina, sistema de corte, ensamble, ajuste y prensado del núcleo, ya que estas actividades son decisivas para conseguir un equipo con menores pérdidas y corrientes de vacío, así como menores niveles de ruido. Se describen las etapas para cálculo del flujo de operación del núcleo, circuito de prueba para la saturación del mismo, consideraciones para realizar la inspección termográfica y medición de las pérdidas de vacío, selección del tipo de lámina y técnicas de ensamble empleadas. Se presentan algunas experiencias como: cambio de medio núcleo, reaislamiento de zonas afectadas empleando fibras Nómex entre láminas, cambio total del núcleo por corte mal realizado desde fábrica, cambio total del núcleo por doble aterrizamiento que ocasionó calentamiento del mismo y afectó el aislamiento de sus láminas dejándolas en corto. En todos los casos se evidencia una disminución de las pérdidas de vacío. Finalmente se presentan el comportamiento de los transformadores después de ser puestos nuevamente en servicio.

Qualified products list 2

The South Carolina Department of Transportation publishes Qualified Products Listings which include pre-qualified materials that may be used on construction and maintenance projects as specified in the project proposal. This document deals with qualified coarse aggregate sources. It is broken down by supplier, location name, SCDOT number, location, fineness modulus, absorption, specific gravity, bulk SSD and soundness loss.

Qualified products list 1

The South Carolina Department of Transportation publishes Qualified Products Listings which include pre-qualified materials that may be used on construction and maintenance projects as specified in the project proposal. This document deals with qualified fine aggregate sources. It is broken down by supplier, location name, SCDOT number, location, fineness modulus, absorption, specific gravity, bulk SSD and soundness loss.

INDOOR MOLD After a Severe Weather Event

Many South Carolina residents are concerned about indoor mold after severe weather events. DHEC has compiled this informational handout with recommendations to guide decisions regarding mold in homes and workplaces.

Qualified products list 2

The South Carolina Department of Transportation publishes Qualified Products Listings which include pre-qualified materials that may be used on construction and maintenance projects as specified in the project proposal. This document deals with qualified coarse aggregate sources. It is broken down by supplier, location name, SCDOT number, location, fineness modulus, absorption, specific gravity, bulk SSD and soundness loss.

SCDOT Qualified Product List 49 - Permanent Traffic Barrier Components

The South Carolina Department of Transportation publishes Qualified Products Listings which include pre-qualified materials that may be used on construction and maintenance projects as specified in the project proposal. This document deals with permanent traffic barrier components.

Evaluation of Appropriate Maintenance, Repair and Rehabilitation Methods for Iowa Bridges, TR-429, 2003

Most states, including Iowa, have a significant number of substandard bridges. This number will increase significantly unless some type of preventative maintenance is employed. Both the Iowa Department of Transportation and Iowa counties have successfully employed numerous maintenance, repair and rehabilitation (MR&R) strategies for correcting various types of deficiencies. However, successfully employed MR&R procedures are often not systematically documented or defined for those involved in bridge maintenance. This study addressed the need for a standard bridge MR&R manual for Iowa with emphasis for secondary road applications. As part of the study, bridge MR&R activities that are relevant to the state of Iowa have been systematically categorized into a manual, in a standardized format. Where pertinent, design guidelines have been presented. Material presented in this manual is divided into two major categories: 1) Repair and Rehabilitation of Bridge Superstructure Components, and 2) Repair and Rehabilitation of Bridge Substructure Components. There are multiple subcategories within both major categories that provide detailed information. Some of the detailed information includes step-by-step procedures for accomplishing MR&R activities, material specifications and detailed drawings where available. The source of information contained in the manual is public domain technical literature and information provided by Iowa County Engineers. A questionnaire was sent to all 99 counties in Iowa to solicit information and the research team personally solicited input from many Iowa counties as a follow-up to the questionnaire.

Organizational maintenance manual (including repair parts and special tools lists) : artillery ammunition for guns, howitzers, mortars, recoilless rifles, and 40-mm grenade launchers.

"December 1973."

Influence of EVA and acrylate polymers on some mechanical properties of cementitious repair mortars

In repair works of reinforced concrete, patch repairs tend to crack in the interfacial zone between the mortar and the old concrete. This occurs basically due to the high degree of restriction that acts on a patch repair. For this reason, the technology of patch repair needs to be the subject of a discussion involving professionals who work with projects, construction maintenance and mix proportioning of repair mortars. In the present work, a study is presented on the benefits that the ethylene vinyl acetate copolymer (EVA) and acrylate polymers can provide in the mix proportioning of a repair mortar with respect to compressive, tensile and direct-shear bond strength. The results indicated that the increase in bond strength and the reduction in the influence of the deficiency in Curing conditioning are the main contributions offered by the polymers studied here. (C) 2009 Elsevier, Ltd. All rights reserved.

Improved Road Design for Future Maintenance - Analysis of Road Barrier Repair Costs

The cost of a road construction over its service life is a function of the design, quality of construction, maintenance strategies and maintenance operations. Unfortunately, designers often neglect a very important aspect which is the possibility to perform future maintenance activities. The focus is mainly on other aspects such as investment costs, traffic safety, aesthetic appearance, regional development and environmental effects. This licentiate thesis is a part of a Ph.D. project entitled “Road Design for lower maintenance costs” that aims to examine how the life-cycle costs can be optimized by selection of appropriate geometrical designs for the roads and their components. The result is expected to give a basis for a new method used in the road planning and design process using life-cycle cost analysis with particular emphasis on road maintenance. The project started with a review of literature with the intention to study conditions causing increased needs for road maintenance, the efforts made by the road authorities to satisfy those needs and the improvement potential by consideration of maintenance aspects during planning and design. An investigation was carried out to identify the problems which obstruct due consideration of maintenance aspects during the road planning and design process. This investigation focused mainly on the road planning and design process at the Swedish Road Administration. However, the road planning and design process in Denmark, Finland and Norway were also roughly evaluated to gain a broader knowledge about the research subject. The investigation was carried out in two phases: data collection and data analysis. Data was collected by semi-structured interviews with expert actors involved in planning, design and maintenance and by a review of design-related documents. Data analyses were carried out using a method called “Change Analysis”. This investigation revealed a complex combination of problems which result in inadequate consideration of maintenance aspects. Several urgent needs for changes to eliminate these problems were identified. Another study was carried out to develop a model for calculation of the repair costs for damages of different road barrier types and to analyse how factors such as road type, speed limits, barrier types, barrier placement, type of road section, alignment and seasonal effects affect the barrier damages and the associated repair costs. This study was carried out using a method called the “Case Study Research Method”. Data was collected from 1087 barrier repairs in two regional offices of the Swedish Road Administration, the Central Region and the Western Region. A table was established for both regions containing the repair cost per vehicle kilometre for different combinations of barrier types, road types and speed limits. This table can be used by the designers in the calculation of the life-cycle costs for different road barrier types.

Applications of precast concrete in repair and replacement of civil works structures /

Mode of access: Internet.

Influence of Antiplatelet Drugs in the Pathogenesis of Experimental Periodontitis and Periodontal Repair in Rats

Background: Platelets contain an array of biologic mediators that can modulate inflammation and repair processes including proinflammatory mediators and growth factors. Previous studies have shown that periodontitis and periodontal repair are associated with platelet activation. We hypothesized that drug-induced platelet inactivation may interfere in the processes of inflammation and repair in experimental periodontitis in rats by suppressing the release of biologic mediators from platelets to the site of injury. Methods: To measure the effects on periodontitis, ligatures were placed around first molars, and aspirin (Asp, 30 mg/kg) or clopidogrel (Clo, 75 mg/kg) was given intragastrically once daily for 15 days. Interleukin-6 (IL-6), tumor necrosis factor-a (TNF-alpha), and thromboxane A(2) levels were measured by enzyme-linked immunosorbent assay. To evaluate the effects of antiplatelet drugs on periodontal repair, ligatures were removed after 15 days of periodontitis induction, and Asp or Clo were administered beginning the following day for 15 days. Periodontal repair was assessed by microcomputed tomography. Results: On periodontitis phase, Asp and Clo significantly reduced levels of TNF-alpha and II-6 (P < 0.05), but only Asp decreased thromboxane A(2) (P < 0.05). Asp and Clo decreased inflammatory infiltration; however, this reduction was more pronounced with Clo treatment (P < 0.05). Histometric analysis showed that Asp and Clo impaired alveolar bone resorption. During the repair phase and after removal of the ligatures, microcomputed tomography analysis demonstrated that treatment with Asp and Clo did not impair alveolar bone repair. Conclusion: Systemic administration of Asp and Clo attenuates the inflammation associated with periodontitis without affecting the repair process when stimulus is removed. J Periodontol 2011;82:767-777.

Optimal scheduling of aircrafts’ engines repair process

We address a real world scheduling problem concerning the repair process of aircrafts’ engines by TAP - Maintenance & Engineering (TAP-ME). TAP-ME is the maintenance, repair and overhaul organization of TAP Portugal, Portugal’s leading airline, which employs about 4000 persons to provide maintenance and engineering services in aircraft, engines and components. TAP-ME is aiming to optimize its maintenance services, focusing on the reduction of the engines repair turnaround time.